The present invention relates to a disk bonding or fabricating system for forming a single disk by bonding first and second disks.
A disk bonding process of one conventional example includes a first operation of placing a lower side disk on a spin coater, a second operation of supplying an adhesive to the lower side disk on the spin coater while the spin coater is spinning at a low speed, a third operation for stopping the spin of the spin coater and overlapping an upper side disk on the lower side disk, a fourth operation of spreading the adhesive between the lower and upper disks by spinning the lower and upper disks on the spin coater at a high speed for a predetermined time duration, a fifth operation for stopping the spin of the spin coater again and transferring the upper and lower disks bonded by the adhesive, to an ultraviolet irradiating unit, and a sixth operation of curing the adhesive layer between the lower and upper disks to complete the bonded disk. The spin coater can form an adhesive layer of a uniform thickness, and improve the flatness and uniformity of the bonded disk.
In this conventional process, the high speed spinning operation of the spin coater is interrupted from the operation of placing the lower disk on the spin coater to the end of the operation of overlapping the upper disk. Therefore, the conventional process prolongs the off time during which the high speed spin coating operation is not carried out, and accordingly deteriorates the duty cycle of the spin coater and the overall efficiency of the system.
When the upper disk is closely overlapped on the lower disk, an adhesive of a low viscosity spreads radially inwards as well as outwards, and tends to flow out from the center hole of the disk. When, on the other hand, an adhesive having a high viscosity requires a long time to spread over a required area.
In the curing step, furthermore, the bonded disk tends to be deformed, warped or corrugated because of heat generated by ultraviolet radiation and shrinkage of the adhesive layer in the setting of the adhesive.